In the fabrication of semiconductor devices, phosphorus is diffused into the surface of a semiconductor such as silicon to form n-type conductivity regions. Phosphorus is deposited on a surface of a silicon wafer in either elemental form or in the form of a phosphorus-doped oxide, typically a phosphosilicate glass. The silicon wafer, with the layer thereon, is then heated to a temperature, typically in the range between about 1000.degree. C. and 1200.degree. C. for a period of time to diffuse the phosphorus into the silicon with the time required for the diffusion increasing with decreasing temperature.
With increasing diffusion temperatures warpage of the silicon wafer can occur and the distribution of dopants added in prior diffusions is changed. It would be desirable to have a method for diffusing phosphorus into a semiconductor such as silicon which can be carried out at a low temperature without requiring an excessive period of time for the diffusion to occur.